When Conducting Inspections, Follow The Lines

In addition to offering “highways and beltways” between nests and food, such utility lines may also offer pests other resources. Various conduits and air handling systems may also be warm, or they will warm a structural void. No doubt, both the warmth and coolness generated by hot and cold water lines within structural voids can offer pests attractive warm or cool micro-environments. The gurgling sound of water passing through pipes is itself attractive to rodents, and they will follow such lines in search of leaks or condensing liquids on the pipes.

REAL-WORLD EXAMPLES. Elementary examples that quickly come to mind are noting the horizontal tree branches touching a roof — of course, such conditions are highly conducive to tree squirrels, roof rats, and carpenter ants gaining entry to a structure. But we must also visualize in our minds those lines which are not readily visible to us, but play as critical a connection as the tree branch roof top example.

Rats and mice in high-rise commercial buildings commonly travel between floors using various electrical conduit lines. Wires of all different shapes and sizes inside our buildings must appear totally natural to the commensal rodents as they have been climbing similar “lines” in their natural world for millions of years as they move up and down twigs, branches, tree trunks, vegetation stems and rock edges.

In supermarkets and office complexes, rodents will travel and nest within the subflooring or suspended ceiling voids following the electrical lines feeding various computer and register systems. These wire chases are critical zones and must be checked. In high-rise buildings, mice will travel vertically following the electrical lines and associated chases and voids that support heating systems. The house mouse is particularly uncanny in its ability to squeeze through and live within the linear voids of buildings. Such areas must be inspected to implement effective long-term rodent control programs. Norway rats travel sewer lines and drainage systems. These subterranean linear systems offer food, water, and protection from many of the above-ground predators.

But it is the roof rat that offers one of the best examples of thinking linearly when attempting to identify rat-active areas. This rat has origins in the jungle where it maintained an arboreal existence. Thus, when inspecting for roof rats, instead of looking first for droppings, I first let my eyes relax, and I allow the various horizontal and vertical lines in a particular area catch my eyes. Long straight tree trunks, outside exterior electrical and telephone lines, fencelines, telephone poles, tree branches contacting roofs, and the various horizontal ledges as formed by construction practices are key locations when inspecting for roof rats.

NOT JUST RATS AND MICE. Thinking linearly also pays off when inspecting for other pests, for example, moles and raccoons. Moles are typically active along the line created where wooded areas meet open areas. They also routinely follow along the linear edge of fence rows, concrete walkways, driveways, and building foundations. These linear areas are excellent for placing mole traps. The raccoon, while traveling through urban and suburban neighborhoods and yards, also uses the linear border created where yard landscaping meets open yard areas.

When conducting inspections, add another dimension to your thinking when attempting to analyze a pest situation. Follow the lines to see where pests are active in and around buildings. By doing so, you , like the animals, can use the short route for gathering resources. In this case, the resource is pest information.

Dr. Robert Corrigan is president of RMC Pest Management Consulting.